AIKEN, S.C.EM is moving closer to closing the first Savannah River Site (SRS) tank farm structures since the closure of an underground waste tank in April 2016.

EM and SRS liquid waste contractor Savannah River Remediation received initial federal and state regulatory concurrence to begin the process leading to operational closure of the structures. The South Carolina Department of Health and Environmental Control and U.S. Environmental Protection Agency have preliminarily agreed that no additional waste removal from the structures is necessary, and that EM may continue to proceed with the formal closure process.

The two structures are known as Diversion Boxes 5 and 6. They are a center of activity, similar in concept to an interstate highway’s on- and off-ramps. Each box can connect waste tanks to numerous destinations by way of a series of nozzles and piping that direct radioactive liquid waste between waste tanks or between a waste tank and a facility.

The diversion boxes have been out of operation for more than 30 years. Both are about 15 feet long, 11 feet wide, and 18 feet deep, and they sit on approximately 4-foot-thick concrete slabs about 100 yards apart in the heart of F Tank Farm, one of two tank farms at SRS. There are a total of 14 diversion boxes in the tank farms.

The next phase for Diversion Boxes 5 and 6 is to prepare formal documentation, which will include an opportunity for public comment, leading to a final decision by the agencies that the diversion boxes can be operationally closed by filling them with a cement-like grout.

Isolating the boxes and obtaining necessary regulatory approvals for grouting is targeted for completion this year. EM is aiming to start filling the boxes with grout in 2022. Diversion Box 5 will require about 94 cubic yards — or about 12 truckloads — of grout; Diversion Box 6, which is slightly larger, will require nearly 113 cubic yards of grout.

DOE-Savannah River Assistant Manager for Waste Disposition Jim Folk said the operational closure of the diversion boxes is another positive step for the site's liquid waste mission.

"Cleaning and grouting structures that have either contained or facilitated the flow of radioactive waste are important actions that help fulfill the overall closure mission," Folk said. “Operational closure of these diversion boxes is a significant step toward our overall plan for deactivation and eventual closure of the entire F Tank Farm.”

Operational closure is a detailed process, as regulatory agencies review plans to ensure thoroughness and safety of the entire process, focusing on safety to human health and the environment for the long term. Closure of the diversion boxes, along with operational closure of waste tanks and other structures, ultimately leads to closure of the entire F Tank Farm.

SRR President and Project Manager Phil Breidenbach said preliminary regulatory concurrence to move forward with operational closure is a significant step in the process of closing diversion boxes and waste tanks.

"Moving forward with another important operational closure would never happen without exceptional teamwork with the state, DOE, and within SRR, " Breidenbach said. "Each step we take moves us one step closer to completing our mission, which is to safely eliminate the greatest environmental hazard in South Carolina. I’m proud of this team and the work we’re doing.”